A segregation approach to molecular weight control in controlled degradation of polymers

In a reactive extrusion process a new approach - degrading only a portion of the input followed by a mixing process with unreacted portion - has been proposed as a method to control the molecular weight and molecular weight distribution (MWD). The number average molecular weight, M n , and the weight average molecular weight, M w , are studied through the Schulz-Zimm molecular weight distribution. The results indicate that M n , and M w can be regulated separately during degradation. M w and the polydispersity index (PDI) of a segregated degradation process are higher than the corresponding results of a uniform system. In the later stage of a segregated degradation the PDI can be higher than that of the original polymers. Starting from a narrow unimodal MWD it is possible to produce a bimodal MWD.